National Aeronca Association Bulletin Board

I know that in our little birds, the calculation of Thrust, does not seem to come up much. Does anyone know about how much thrust a stock A-50 or A-65 can produce at Red Line with the propeller normally used?

Bob

Bob,
There are a lot of variables that come into play with this calculation. Speed of the aircraft and the speed of the propeller effect the angle of attack of the propeller blade. Density of the air and propeller disc also play into it.
Wood props are going to be different than metal due to the centrifugal twisting forces and aerodynamic twisting forces.
he best way to determine your thrust is to hook up a dynamometer from the tai to a stump and give it a go.
Paul

Thank Paul. I understand the inaccuracies of trying to calculate this, but wondered if like, say turbine engines, if they have some Rated Thrust. A friend is trying to determine the relationship to this and his newly build airboat, which of course depending on what media it is on has much difference movement resistance.

Bob

Tie a spring scale (guess the size, 600 pounds maybe) to an immovable object and the other end to the tail of your plane. Slowly advance the trottle with someone reading the thrust in pounds. It will get you in the ballpark. Oviously if the scale max out, you'll need a larger scale or if it does move very much, you'll need a smaller one.

It would be interesting to know what readings you get.

Dennis

Bob,
The thrust calculations are generally reserved for turbojets and turbofans by their design, for comparison. Our little engines, and turbo-shafts and turbo-props are torque producing engines and use horsepower as the comparison factors. It's not as cut and dry as just horsepower and thrust.
Paul

I understand about the HP Vs. Thrust situation and actually don't really care about it for my airplanes. If the engine gets me up in the area, helps me scoot around and some reasonable pace and gets me home, I am fine. This is for an A-65 mounted on a two pontoon air boat. Should be jut fine for over the water, but trying to find out what it MIGHT do over, Ice, Reeds and on land, which I do not expect will work at all.

Bob